In commercial and residential buildings, electrical boxes are used to house outlets that distribute power, switches that control lighting and virtually any type of receptacle that carries electrical signals. These electrical boxes are usually installed during construction of the buildings before walls or panels are secured to the joists and studs. Rectangular openings are cut out from the wall panels to allow access to the installed electrical boxes.
An example of this type of prior art electrical box is shown in U.S. Pat. No. 4,165,443 by Figart et. al. issued Aug. 21, 1979, in which an electrical box system for mounting modular switch and receptacle units to a wall is disclosed. The receptacle units have special shapes with elongated terminals protruding from the backside, which fit into complementary openings within the electrical box. Power and distribution cables connect directly to access openings in the box, and are routed to the receptacle unit terminals through a bus plate array. The electrical box is mounted to a wall stud using a mounting bracket having mounting slots and lips that correspond to mounting slots and lips in the electrical box. Once the mounting bracket is secured to a wall stud, the electrical box can slide into its corresponding slots and lips. This system is disadvantageous in that there is no method to secure the electrical box to any structure other than a stud within a wall. This is not always acceptable since the placement of an electrical box is frequently determined by function or desire rather than the location of existing wall studs. Another disadvantage is the necessity for screws and tools to fix the mounting bracket to the stud, which reduces the overall ease of installation of the electrical box.
The limited placement ability of the electrical box is addressed in U.S. Pat. No. 5,500,487 by Leon issued Mar. 19, 1996 and U.S. Pat. No. 4,485,282 by Lee issued Nov. 27, 1984. Leon discloses a simple electrical box having contacts inside the box for making electrical connection to removable switch or receptacle units. The switch and receptacle units have special shapes that allow them to be inserted within the box that avoids incorrect electrical connections. This electrical box has the capability of being installed at any position in a wall, but requires screws and tools to fasten its securing tabs to the wall.
Similar to Leon, Lee discloses a base, similar to an electrical box, with niches that can accommodate removable switch or receptacle units. A mechanical system ensures that the units can be locked into the base to prevent unwanted removal of the switch or receptacle units. This system also requires the base to be secured to a wall with screws.
Both Leon and Lee overcome the limited placement problem of Figart et. al., but still require screws and tools in order to secure the respective product into a wall, which is time-consuming and cumbersome. Furthermore, an electrical box secured to a wall by screws can become unstable after installation.
U.S. Pat. No. 4,500,746 by Meehan issued Feb. 19, 1985 shows a self-contained electrical box that can either be a receptacle or switch. The power supply wires are pressed into the back of the receptacle without the need for stripping off the insulation from the wires to make electrical contact. A screw engages a pawl in the back of the unit that eventually sandwiches the wall between the pawl and an external securing tab of the electrical box. This particular feature is an improvement over the inventions of Leon and Lee in that the electrical box remains more stable and secure in the wall. Installation of this electrical box is still somewhat time consuming since a tool is required for setting the screw.
U.S. Pat. No. 4,215,787 by Moran, Jr. et. al. issued Aug. 5, 1980 discloses an electrical box with moulded wedge-shaped retaining stunts for easy insertion and securing of the electrical box at any position in a wall. The electrical box can accommodate any receptacle unit. As with Leon, Lee and Meehan, this electrical box does not have to be fixed to a stud. Additionally, the retaining stunts can ensure that the electrical box remains stable within the wall. The distinctive feature of this electrical box over the previous references is that no screws or tools are required for its installation within the wall. However, the stability of the electrical box depends on the precise opening in the wall. The opening must be complementary in size and configuration to the open front side of the box. A slightly enlarged opening can result in an electrical box that is unstable in either the vertical or horizontal directions within the wall. It is even possible for the electrical box to be pulled out from the opening in the wall during normal use as a power outlet if the opening is too wide. Therefore, this electrical box has a very low tolerance for variations in wall opening sizes, especially in the vertical direction, and is difficult to securely lock into place.
The system shown in U.S. Pat. No. 4,847,444 by Holland, issued Jul. 11, 1989 includes an electrical box holder which can snap into an opening cut out from a wall. The electrical box, affixed with any receptacle unit, can be firmly secured by the holder within the wall. This is achieved by sandwiching a wall edge between outer lips and inner edges of the holder. Spacers can be attached to the inner edges of the holder to reduce the spacing between it and the outer lip in order to accommodate thinner walls. Although the holder is more stable than the electrical box of Moran, Jr. et. al., screws and tools are required to secure the electrical box to the holder.
U.S. Pat. No. 4,226,393 by Rardin et. al., issued Oct. 7, 1980 discloses an anchoring device for securing an electrical box within a wall. The electrical box snaps into the anchoring device that comprises of wedge shaped resilient fingers for allowing easy entry into an opening cut out from a wall. Clamps are secured to the anchor device via screws such that the wall is sandwiched between the fingers and clamps. Even though the electrical box is quickly secured into the anchoring device, the anchoring device itself will not remain secure within the wall until the clamps are screwed to the anchoring device to lock the anchoring device to the wall. This method of installation is still rather cumbersome and time consuming.
There is clearly a need for a quick connecting electrical box system in which an electrical box can be firmly and reliably secured within an opening in a wall without the use of any screws and tools.